Now, I've seen a lot of people place so much emphasis on PINGING backlinks in order to get them indexed on time. Now to be fair, I actually jumped on the bandwagon initially, and tried EVERY pinging technique you could possibly think of, without any of them making much of a difference. Then as I became more experienced in SEO, I began to realize that the important thing isn't pinging links, but BUILDING THEM!.....Yes. The time you spend pinging links could be better spent building new ones. And moreover, MAJORITY of the links that do not show up on Yahoo site explorer STILL GET NOTICED by the search engines, and are still credited to your website. I have noticed this from experience. So fellas, I encourage you all to focus on building quality links, and leave the rest of the work to the search engines to figure out. Hope this helps? All the best!